Aspects of leukocyte physiology to be studied will be: A. The lymphatic system: We will further explore the physiological basis for the high rate of IgG production by marrow lymphocytes from normal human subjects, as shown by this laboratory. We hypothesize that this process may be involved in tolerance of tissue-specific antigens as they develop in ontogeny. Another aspect of immunoglobulin production which will be further explored is in Hodgkin's disease, where we have demonstrated a markedly increased IgG production by lymphoid cells in lymph nodes and spleen histologically uninvolved with the disease. We will continue to apply criteria such as in vitro blastogenesis to non-specific and specific mitogens, surface immunoglobulins, lymphotoxin elaboration and rosette formation to lymphocytes and leukemic cells. We are aware that present criteria of T and B cell definition are not firm, but we believe that such attempts to categorize cells on a functional basis are imperative for a better understanding of hematological malignancy. B. Bone marrow stem cell function: A human marrow transplantation program has been started and this program offers several opportunities for study by this program. One aspect which is currently underway concerns acquisition and cryopreservation of marrow in selected cases of CML and AML in remission. The capacity of such preserved marrow to form granulocyte-monocyte colonies has been demonstrated. The feasibility of such autologous-preserved marrow in reconstituting hemopoiesis in terminal leukemic progression, after patients receive supralethal cytotoxic therapy, will be assessed. C. Marrow growth in soft agar and characterization of CSF: The capacity of marrow from patients with various hematological problems to respond to a standardized CSF stimulus in vitro will be assessed with the major objective of separating those instances due to failure in CSF activation or production from those in which the colony forming cell (CFC) is incapable of responding to active CSF. The mechanism of CSF production, activation and impingement on CFC will be dissected. Our evidence to date points to interaction between plasmatic constituents of complement system and cellular products (lysosomally contained) for CSF activation.